Cardiotomy reservoirs are used during major surgery to collect blood which has been accumulated in a surgical incision site or elsewhere by an air driven cardiotomy sucker or the like.
It is very desirable to reinfuse this blood into the patient since the patient's own blood is far superior to any donated blood that he can receive. However, blood which has been removed from the surgical field is likely to contain small clots and other forms of solid debris, which should not be reinfused into the patient. In addition, because the cardiotomy suckers typically receive an air/blood mixture (because the blood is picked up by suction) the blood must be defoamed before it is returned to the patient's bloodstream.
Hence, the air/blood mixture is passed into the cardiotomy reservoir, where it is defoamed and where it may be passed through a filter to remove undesirable solid debris. The blood can then be stored in the cardiotomy reservoir under blood preserving conditions until the surgeon elects to return the blood to the patient.
Prior cardiotomy reservoirs, such as those disclosed in U.S. Pat. Nos. 3,891,416 and 3,507,395, which are commercially available and widely used, suffer from certain disadvantages that limit their effective use. In the prior devices, the defoaming agent is typically carried by a spun metal or plastic fiber sock which extends along a substantial portion--if not the entire length--of the cardiotomy reservoir. On entering the reservoir, the air/blood mixture from the cardiotomy suckers is channeled to the interior of the defoaming sock. Under generally prevailing conditions, at least a substantial portion of air will usually migrate through the defoaming sock, to be manually vented to the atmosphere. This reduces the efficiency of the prior devices since the defoaming capability of the sock deteriorates when air is forced therethrough. In the prior devices, this has necessitated the use of a very large defoaming sock to maintain acceptable levels of efficiency for even a few hours.